Handover, or handoff, is a technology for switching a connection of a mobile node from one network to another network while maintaining ongoing communication session.
Typically, handover means a horizontal handover occurring between homogeneous networks. The notion of vertical handover has been introduced with the deployments of different wireless technologies-based communication networks, and various vertical handover technologies have been developed and standardized to efficiently switching the connection of the mobile node between heterogeneous networks. Unlike the horizontal handover occurring between the homogeneous networks, e.g. between Wireless Broadband Internet (WiBro) networks, the vertical handover is a handover occurring between the networks using different technologies, e.g. a WiBro network and a cellular network such as 2nd Generation (2G) or 3rd Generation (3G) network or an Institute of Electrical and Electronics (IEEE) 802.11-based Wireless Local Area Network (WLAN).
In the vertical handover method, a pre-registration procedure is performed to authenticate the mobile node prior to the execution of the vertical handover, such that the handover to a target network is performed quickly without additional handover preparation process. However, there is no detailed signaling mechanism specified for handover request or instruction to serving network, whereby the data forwarding from the serving network to the target network is likely to fail, resulting in data loss.
There is therefore a need for a data forwarding method that is capable of minimizing the data loss during the vertical handover between heterogeneous networks.